Mysterious chronicle (part 23) is a book found only in Daemonheim. It may appear in front of the dungeon-ending ladder after killing a boss monster.

Written in the year 0 of the Fifth Age. Bilrach hears that some are calling this the beginning of the Fifth Age. He thinks that would be suitable only if they weren't calling it the Age of Man. He re-names it the Age of Reckoning. He allows the humans three hours to celebrate before going back to work, as revelry leads to rebellion, and he cannot afford to massacre them as he gets so close to The Rift.

Bilrach must still have some form of contact outside of the dungeons to know that it is the beginning of a new age, or at least someone in the group with Bilrach does.

I've heard that some are calling this the beginning of the Fifth Age; it would seem suitable if they weren't calling it The Age of Man. Bah! I rename it The Age of Reckoning! I will allow the humans three hours to celebrate, and then we work again. I will not allow them any longer than that: revelry leads to rebellion, and I cannot afford to massacre them as we get so close.